Notes

Hellions give you complete map control until the Zerg can counter you with Roaches or Mutalisks. Take advantage of this and make sure you clear the watch towers.

Be aggressive with your early Hellions and try and pick off Drones without taking too many losses.

Alternatives

The correlation between tech and expand timing are very important with regards to the mid game potential of this build. While the reactor variant is somewhat more popular, there is another variant which is slightly different in the early game:

With this build, you can begin your Command Center about 20 seconds earlier, at around 4:20. The drop timing will be slightly later due to going Barracks first as opposed to gas first, but at the same time the greater mineral income allows for stronger mid game pushes.

An alternative build would be a two base equivalent to hit between 8:30 and 9:00 with a strong set up for a Mech-based game(Order of getting things is much more important than the supply count).

1 Rax FE into BF Mech

10 Supply Depot

12 Barracks

15 Orbital

15 Marine

16 Supply Depot

CC at natural

Factory(1) once 100 gas, but do not cut SCV production

Factory(2) @ next 100 gas

Tech Lab on Factory(1) immediately upon Factory(1) 100% -> Starport

Reactor on Factory(2)

@100% Starport -> Medivac

For effectiveness, build needs to hit at or before 9:00 minutes.

From here the Terran player should take gas 3 and 4, put a TL on the Starport for Banshee production, add a third Factory and go into a Mech play.

Starting with a 1 Rax FE into Double-Gas this build is a much better set up for the mid and late games than the original "Slayers build". Zerg's will typically begin their army production at the 9 minute mark having defended using minimal defence and Queens[1]; this is the period where delaying army production is most important. If any all-in is scouted, cancel BF and start Tank and Siege Mode.

Execution

After your opening you should have at least 5 Blue Flame Hellions and several Marines. With these units move out across the map and try and deny scouting with your Hellions. Move your units to a ledge near your opponent's base and drop them into your opponent's base elevator style.

Be active with your Hellions and try and get a good angle with them. The more damage you do with this push will either win you the game or severely cripple an unprepared Zerg.

Be careful to not lose the Hellions unnecessarily - if possible, you should pick up your Hellions with your Medivac before they die. This will strongly reinforce any mid game push, as well keep the Zerg wary of further drops - be they a prelude to a large push or simultaneous with a push.

Followup

There are many followups to this build. The best followup is dependent on what you scout the Zerg doing, as well as how risky you want to play. Keep in mind that the variability of the followups associated with its build is a very strong point that you should make use of, especially in series play.

There are a few general guidelines that will help you better understand the available followups:

Keeping an eye on the drone count at the natural expansion is key. If the Zerg is saturating the natural relatively quickly, then you have a window for an early attack, but you must get there are quickly as possible, preferably in the 8:30-9:00 range.

You do not actually need to tech any further nor do you need to expand. If you can keep the Zerg in the dark about whether you are expanding and whether you are teching, you will have won yourself an important victory in the battle for scarce information.

If you opt for a stim push, it is best that you start stim slightly before 6:00, and make sure you move out before stim is done if you have ascertained that moving out is actually safe. Whether or not it is safe to move out is something you will have to determine using your Hellions. The goal is to engage at the Zerg's natural just as stim finishes. However, if you opt for a stim push, you will not be able to attack with an effective siege push. Thus you will have to choose whether to go with stim or whether to go with siege mode after the initial Hellion harass and Blue Flame tech.

Do not build your extra two Barracks until you have 300 free minerals. At this point, build the Barracks simultaneously.

Roach+Spine Opening

If the Zerg is defending your initial Hellion harass with Roaches and a couple Spine Crawlers, then a 3rax stim followup in combination with Hellions will be very strong. You will need to immediately build a Tech Lab on your Barracks so you can begin stim before 6:00. You will need to immediately cut SCVs and put down two more Barracks as soon as you have 300 minerals. Assuming that you have 21 SCVs already at this point, you will need to immediately stop SCV production.

Once you finish your extra Barracks, swap one onto the Reactor that was on the Factory. Put a Tech Lab on the other Barracks so that you have 2 Tech Labs and a Reactor. With this you will be production Marauders out of each Tech Lab and reactored Marines. Any extra minerals will go into Hellions. Be extremely sure not to miss any Supply Depots - you do not want to have production halted at any point, as the timing is rather strict.

Move out depending on when you started stim - just be sure that you will arrive at the natural just as stim finishes. Until then, use your Hellions to do as much damage as possible but do not lose them. Remember - you outrange both Queens and Roaches. It is possible with very crisp micro to get free hits onto both units. You want the opposing force to be as damaged as possible when you arrive with the stimmed bio, which is the real DPS source. The Hellions are there as backup only to do with any Zerglings, as well as Drones which may be pulled.

Ling+Spine Opening

A one base bio all-in is significantly riskier against mass Speedling, as the relatively inefficient resource per Larva cost associated with Zergling production means that the Zerg can make greater use of spawn Larva rounds. This translates into a faster rate of increase of mining, as Drones can be produced at a faster rate than if the Zerg had gone Roach+Spine. There are certain variables involved - if the Zerg only goes for a few Roaches, say 4 or 5, then it is possible that the Zergling+Spine Zerg will actually have a lower income, assuming that a large quantity of Zerglings are made. Even so, going 1 base against a mass Zergling build is dangerous, even if the subsequent income for the Zerg is lower than that for the Roach+Spine opening. This is because Zerglings in mass are extremely effective against bio, even more so when Banelings and +1 attack are added. As such, if you are going to one base the Zerg, then it will be necessary to bring Medivacs as well and micro to a heavy extent.

Standard Followup

Generally, given that you began your expansion between 4:20 and 4:40, you will play out a standard macro game. There a few strong mid game followups if you choose this route.

If the Zerg is skimping on units, you can go for a 3 Tank siege + Marine push which arrives at the Zerg base around 9:00. This was used by a random Korean masters Terran against DongRaeGu in the GSL Code A qualifiers to great success, result in the destruction of the Zerg natural for almost no loss.

If the Zerg is making quite a few units. then set up a sim city in your natural, and expand in a safe manner while relying on constant and multiple drops to harass the Zerg. You will want to have a couple Thors in conjunction with any late game (>16:00 game time) push.

Another possible followup is to hit with a large stimmed Marine + Blue Flame Hellion push around 10:30, after a series of drops. This build follows the gas first build order in order to begin dropping as soon as possible.